Tempus Bellum
by Harry Ferguson
Summary: UP FOR ADOPTION!On the morning of his 17th birthday, Harry Potter awakes to find a very mysterious letter and parcel among his belongings, what happens next could risk the fate of the world…This is my first attempt at a Doctor Who xover so please be kind
1. Prologue: Out of Sight, Out of Mind

**Tempus Bellum**

**Summary: **On the morning of his 17th birthday, Harry Potter awakes to find a very mysterious letter and parcel among his belongings, what happens next could risk the fate of the world…

**A/N: **I do not own Harry Potter or Doctor Who. But hat's off to J.K and erm… the B.B.C…Takes place post HBP. –HOWEVER- The idea of Horcruxes in this universe are non-existent. (and no I'm not explaining why or how.)

**Prologue: Out of Sight, Out of Mind**

James Potter was slowly falling asleep. He and his wife Lily had been running from a certain Dark Lord for a little over two years. They were looking for a way to defeat him once and for all but had exhausted their resources. So when their son was born, they decided to go into hiding.

James was, well, a regular guy. But there were times where he would… act strangely… around certain areas or people. James remembered once when he went round muggle London after a trip to Diagon Alley…

_He was walking through the Isle of Dogs when it happened. James was glad he was with Sirius because he suddenly felt light-headed. Images of strange metal men and dustbin like objects were swimming in front of his eyes. Grabbing his friend's collar he sank to his knees._

"_Oit James, what you playin' at mate?" his friend asked, a look of annoyance in his eyes._

"_Wha…what? Oh… sorry I felt light headed for a sec." James replied standing once more._

James was abruptly shaken from his thoughts as an almighty boom echoed through the house.

"JAMES!! HE'S FOUND US!" Lily cried rushing towards the stairs.

"LILY, GET HARRY, I'LL STAY HERE AND HOLD HIM OFF."

"JAMES YOU CAN'T!"

"I'M NOT ARGUING NOW GO!!"

With that James drew his wand and motioned Lily to make sure Harry was safe.

Running towards the front of the house James suddenly felt dizzy.

"Ah… 'Potter' at last I have found you." The cold shrill voice of Lord Voldemort rang out. "I shall once and for all end this… multi lifelong battle."

"What are you talking about?" James spat.

"Oh yes, _human._ I'd almost forgotten. No matter, this ends tonight."

"What on Earth are you on about?" James screamed.

"What on _Earth_? Hmmm, this human version of yourself really doesn't do you justice." Voldemort sneered.

"However, as I said this no longer matters. You were a worthy opponent, I'm almost sad that this has come to an end…"

Before James could react, he was hit in the chest by a green orb of light.

As Voldemort stepped over James' dead body he whispered into his ear.

"Goodbye… Doctor."


	2. Chapter One: A Birthday Change

**Chapter One: A Birthday Change**

Harry Potter lay in a breathless sweat. He'd woken up from a nightmare about the night his parents died, he thought it strange however, that he had seen everything through his father's eyes.

He sat in silence for over two minutes before sitting up and putting his glasses on. He looked around Ron's room, sunlight barely breaking through the window. Noticing that the youngest Weasley had vacated the room, Harry picked out a set of robes and padded towards the bathroom.

He was glad he'd moved to the Burrow so quickly this year. He knew that if he stayed with his aunt and uncle after his birthday the wards that protected him would come to an end. So he owled Mr and Mrs. Weasley and asked them if he could move in with them. In the letter he said that it could be dangerous for them to do so and that he'd pay for any extra wards they would need.

They replied quickly and had reluctantly agreed to accept the money for the wards. They had set the wards up the day before his birthday and had told the constructors that they would be paid the next day. Harry thought over this as he dressed and walked down to the Weasley's Kitchen.

"Morning Harry dear, Ron's with Arthur out in his shed, he said that he had something out there that might be beneficial to you." Mrs. Weasley smiled at him. "Oh and Harry, happy birthday."

Harry smiled at Mrs. Weasley and stifling a yawn walked out into the yard. Spotting a mop of red hair he walked over to the small shed.

"Morning mate," Ron said, shifting a few boxes, "give us a hand?"

Harry chuckled and set to work. Before long the shed was cleared and Mr. Weasley called the boys towards him.

"Now where is that thing…" mumbled Mr Weasley, "I know it's in here somewhere…"

He fumbled through some boxes for a few minutes then straightened up holding a small silver pocket watch.

"Harry, this watch was one of the only things found in the remains of your parents' home. It was passed to my department as a precaution in case it had been tampered with. However no one has been able to open it. Maybe you have the magic touch…"

Taking the watch, Harry looked at the markings on the back, they looked familiar but he couldn't remember seeing markings like this anywhere before. He turned the watch over and opened the case, suddenly he felt nauseous and fell to his knees. Pictures of weird creatures flashed before him as well as a vivid image of a strange blue box…

"Harry! Harry wake up!"

The world came into sharp focus and Harry sat bolt upright.

"Well, I've heard of DNA transformation before, having gone through it twice myself, but transmutic displacement? They're the ideas of myths. The very idea that someone else with a similar biological matrix as my human self could open that watch was laughable. Until now that is…"

Harry frowned and looked round for the source of the voice. He looked at Ron who was staring at at him in awe and confusion.

"What is it?" Harry said, his frown deepening.

"Ahem, Harry it appears that the watch had indeed been tampered with…" Mr Weasley said his own brow furrowed.

"This old thing?" Harry said holding the watch in the palm of his hand, "nope, there's no way this ol' thing's been opened for years. Only I'm supposed to be able to open this, it appears however that this body is not my own. Therefore I assume my human body was destroyed."

Harry's mind seemed to be moving faster than he could keep up. Before he knew it he was speaking again.

"Ah… I appear to have found out who this," he gestured at his chest, "is in relation to myself. It seems that I was fortunate enough to have a family during my human life and strange as it sounds, I now reside in the body of 'my' son…"

Ron and Mr. Weasley looked horrified, so 'Harry' explained further.

"Don't worry! He's still in here with me and I can tell he's feeling the same way you are. Everything will be explained in due time. I need to run over some things for the time being though, I'll still be around but I'm sure you'd all appreciate it if I left Harry here with you." With his piece said, Harry's body tensed and a few moments later he opened his eyes and smiled.

"Well, at least now I get to find out what my dad's really like and what he thinks about me…"


	3. Chapter Two: Questions

**Chapter Two: Questions**

Harry, Ron and Mr. Weasley walked back to the Burrow.

"Blimey Harry, I'm glad I'm not you at the moment." Ron breathed.

"Why's that?" Harry asked, looking puzzled.

"Well, I don't think I could take it if _my _dad was in my head!" Ron stated.

"I'm not sure if I should be offended by that or not!"

Mr. Weasley chuckled as he opened the kitchen door.

As a group they moved into the living room, looking round Harry was pleased by who he saw.

Hermione was there of course, playing exploding snap with Ginny. His eyes then moved over Fred and George, then to Bill, Charlie, Molly, Remus Lupin, Tonks and…

"Luna?" Harry frowned. "It's good to see you, though I have to admit I'm a bit surprised…"

Luna smiled and moved forwards.

"Well I could hardly miss the day 'The Boy Who Lived' comes of age now, could I?" she mused.

"Erm… I suppose not…" Harry mumbled, grimacing slightly at the comment. Luna on the other hand was beaming at him. Fully. A broad grin had crept across her face. Leaning in she whispered.

"Plus, you happen to be one of my best friends and… Harry did you know there's something different about you?"

Harry blinked at the blonde haired witch and stared in shock.

"How did you…" he started, but before he could finish Mrs. Weasley pulled out a large sponge cake with the words 'Happy Birthday Harry' iced on the top. As everyone began to sing, Harry heard a voice inside his head.

_"Seventeen? So I've been hidden away in that watch for the best part of two decades… Well, I hope Martha's ok…" _

Harry tried to send a mental question to his father. It appeared to work as a few seconds later the voice spoke up again.

_"I'm not quite sure what happened here. Martha was… a friend of mine. We used to travel together, before I became human and met your mother that is."_

Harry, who had been listening to his father's words, was suddenly pulled back to reality as his cake was held out in front of him.

"Make a wish mate." Ron said, obviously eagre to tuck in.

Distracted, Harry blew out the candles and when everyone began mingling round the room, he found an empty armchair, closed his eyes and struck up a mental conversation with his dad.

"_You keep saying about being human, what do you mean?" _He thought, determined to find out as much as he could about his family.

"_Well…" _James began. "_It's a long story, I'll show you later if you like, what I'll say now is, I'm from another world, well… another galaxy in fact. A planet called 'Gallifrey'"_

"_Wait a second, are you telling me you're an alien?" _Harry asked. If anyone thought it was weird that he looked surprised that Ron had just beaten Lupin at a game of chess, no one commented.

"_Look, I promise you I'll explain everything, but it's your birthday! Go and enjoy yourself!" _James' voice faded and the sounds of the room suddenly came back into focus.

"Right!" George said, sitting on the arm of Harry's chair. "I think it's time you opened your prezzies, don't you agree brother of mine?"

"That I do oh devious duplicate!" Fred joined in. "It's not everyday our ickle Harrikins turns 17!"

Grabbing Harry under the arms, Fred and George frog marched him over to a fairly large table piled with gifts, among which Harry spotted a long, thin parcel.

It was about half the length of a wand box and attached to it was a small envelope.

Subconsciously recognizing the scrawl, Harry tore the envelope open and read the note inside.

_Harry,_

_First off: happy birthday!_

_I can't say much but you found the watch so I know that'll help to_

_Answer some questions you might have. The key taped below is_

_HIGHLY IMPORTANT.__ It opens something that is hidden inside the_

_Room of Requirement. Don't worry about what it unlocks, you'll_

_Know what it is when you see it._

_T__he package that this letter came with contains a 'Sonic Screwdriver'_

_Treat this as a second wand. __KEEP IT WITH YOU AT ALL TIMES!!_

_Much luck in the future._

_The Doctor_

_P.S: Keep your wits about you this Christmas!_

Harry re-read the letter a few times, new questions forming in his mind. _What does this key unlock? What's a sonic screwdriver? Why do I need to keep it with me at all times? _He felt his father questioning some things as well and decided to ask him what was going on.

"_I don't have a definite answer for you, this letter appears to have been written by our future self. Which is good news as it means we haven't died at this point, or at least, not for the final time. I can tell you what the key and the sonic screwdriver are for though."_

"Harry, are you feeling alright? You've been staring at that letter for about five minutes…" Fred asked in a worried tone.

"Hmm? Oh, sorry I'm a bit distracted, I think I need some fresh air, can you let everyone know that I'm walking into town?" Harry asked picking up the box that contained the screwdriver. "I'm fine honestly, it's just that there's something in this letter that I need to sort out sooner rather than later. I won't be gone long."

Fred and George both nodded, Harry thanked them and silently walked out of the house.


	4. Chapter Three: Old Friends

**Chapter Three: Old Friends**

Harry sighed as he made his way through Ottery St Catchpole, the summer breeze ruffling his hair as he headed towards the main road.

There was a slight _pop_ as Harry stuck out his wand arm and as the familiar purple bus pulled to a stop his father's voice spoke up.

"_A triple-decker bus? My God you humans never cease to amaze me." _James chuckled.

Harry rolled his eyes and paid for a ticket to Diagon Alley. He might as well pay for the wards as he was out.

Two minutes into the journey, Harry felt light-headed. Falling to the floor his vision blurred as his glasses left his face, images swimming before his eyes.

Strangely, the images came into a sharp focus, looking around he appeared to be in a vast room with a strange console in the middle. Staring round the room in amazement he jumped when he heard a voice behind him.

_"Martha, I'm sorry it's come to this, but I can't risk taking you home, it'd put…" _

_"My whole family in danger I know, I don't mind staying here, the eighties are as ok as anything I guess." The woman who spoke, Martha, was a tall black woman who looked to be in her mid twenties._

_"If there was any other way…"_

_"But there's not! Look, stop beating yourself up about it, it's not an ideal solution I admit but it's better than death."_

_Harry looked round to see who Martha was talking to and gasped when his eyes fell upon the image of his father wearing what looked like a pin striped suit, trench coat and…muggle trainers…_

Harry was violently brought back to earth as the Knight Bus pulled to a stop outside the Leaky Cauldron.

As the bus vanished from sight, Harry walked through the pub, waving at Tom the barman on the way.

Tapping the old bricks with his wand, the hairs on the back of his neck stood on end. As the wall opened leading to Diagon Alley he didn't just sense that something wasn't right here, he knew it.

Walking through the rows of shops Harry felt the air around him grow cold, he gritted his teeth, waiting for the familiar screaming to start, but what happened was far worse. Images of burning planets and civilizations were the only things he could see. The sounds of billions of people's dying screams seemed to ring out around him. Falling to his knees, a cold high voice cut through him.

"Harry Potter, I was hoping not to run into you for this. No matter because I now have in my possession something that will change the world as you know it forever!"

Harry's reply shocked both himself and Voldemort into a dumb silence.

"You've threatened me like this time and time again, we've fought across the vastness of space and time and I always find a way to stop you. What makes you think this time is any different? Master."

Voldemort's mind had shut down. He stood rigid as if he'd been turned to stone.

Luckily, Harry recovered first. Or rather… part of him recovered. He could feel himself move, but knew that it wasn't due to him. His father had taken over in this situation, so Harry mentally shrugged and let him do what he thought best.

Standing, he felt himself rummaging through his jacket pocket. He pulled out the sonic screwdriver and after changing a few settings, he disappeared.

---------------------

The portrait of Albus Dumbledore was enjoying a nice game of snap when a figure faded into view.

As the figure came into full view he realised that it was Harry Potter. Realising Harry was staring straight at him, he blinked and moved back to his own picture frame.

"Good morning Albus," Harry said. "I just thought I'd let you know that 'Voldemort' has attacked Diagon Alley."

"Thank you Harry, what's the current condition of the battle?"

"Battle? Oh no, there wasn't a battle. As soon as I appeared he froze. I also made sure that no one apart from myself can enter AND I made sure everyone EXCEPT Voldemort can leave." Harry said grinning.

"But… Harry… You've left one of the darkest wizards of all time alone in Diagon Alley, from which he can get to Knockturn Alley and seize even more power!" The twinkle in Dumbledore's eyes faded.

Harry sat down and sighed.

"You're right," Harry grimaced. "Unless…" he grinned up at the portrait, "unless I had this." Harry reached into his pocket and showed Dumbledore the sonic screwdriver.

"Harry, where did you get that?" Dumbledore said, his normally calm manner no longer present.

"This? Oh, I've had this for a while. Surely you remember what happened in '45?" seeing the shock on the old headmaster's face, Harry nodded grimly. "I see you do, I couldn't save her and you more than anyone on this planet should know how dangerous it is to mess with time."

Standing to leave, Harry heard three words he hadn't been expecting.

"I know, Doctor."

---------------------

Leaving Dumbledore's office Harry set of at a run for the room of requirement. It had been too long since all this began and he needed to get to the bottom of this as soon as possible.


	5. Chapter Four: At Last Some Answers

**Chapter Four: At Last Some Answers**

Harry skidded to a halt opposite the tapestry of Barnabas the Barmy. He pointed the sonic screwdriver at the wall and waited for the door to appear.

After roughly a minute, the wall flickered and the door appeared, but it wasn't the normal door to the room of requirement.

It had similar ancient symbols carved into it like the back of his father's watch.

Harry didn't stop to think over this however, he was finding it increasingly difficult to find the line where he ended and his father began.

He walked into the room and, closing the door behind him, smiled across at the old blue police box.

"Hello old girl." He said, running a hand over the wooden frame. "It's been too long."

Moving like a kid on Christmas morning Harry fumbled for the key, finding it he jammed it into the lock and threw open the door. He closed his eyes, listening to the subtle hum of the machine before him. Smiling widely Harry jumped into action, he ran forward and started fiddling with the controls.

A few minutes later, a small panel in the floor opened. Nervously, Harry peered into the gap and, sighing slightly, he wrenched it open.

A bright golden light burst from the opening flooding the room with colour. Harry tried to scream but his jaw had clenched and all of his muscles had stiffened. He felt himself rise of the floor and his back arched as he felt a wave of energy smash over him, his arms thrown wide.

Ten minutes later he groggily opened his eyes and looked round. It was as if he'd never seen before. Gone were his glasses, which now lay abandoned on the cold metallic floor.

"Well," he muttered to himself. "At least things are more in focus… In more ways than one… Right… Where was I? Ah, yes…" he pulled a lever and felt a small shudder as the Tardis sprang into life.

He knew that to an outsider the time taken to travel from Hogwarts to Diagon Alley would seem instantaneous but Harry had deliberately calibrated the controls so time slowed down inside the Tardis, for him the trip would take a good couple of hours.

During this time he wandered the vast hallways of the Tardis, memories flying at him from every angle.

He finally knew the real reason why he didn't die as a baby, he understood why James seemed so different after he left school and why Dumbledore had let him handle so much so young. He was a Time Lord and for the first time, he accepted his fate.

With twenty minutes till his confrontation with 'Voldemort' He decided a change of attire was in order.

He thought about wearing the old pine stripe suit and trainers, but that was his father's style, he needed something that was timeless, but that showed his own personality.

He rummaged around and after ten minutes settled on a look that he thought brought out the best in himself.

He wore black combats trousers, boots and a pure white t-shirt that clung to him like second skin with a brown leather jacket over the top. Smiling he returned to the consol room.

While he'd been trying stuff on, he'd noticed that he looked different, not remarkably so, just small details.

He's hair was still dark, but was now a dark brown instead of black, he was slightly taller and his muscles where more defined. He no longer needed to wear glasses either, all in all Harry was glad for the change. However the small lightning bolt scar was still visible on his forehead, though even that had changed in size, it was now only a few millimetres long and almost completely matched the colour of his skin.

Harry sighed, he'd flopped down into an old chair and began riffling through some old text books that were on the floor beside him. He'd started reading 'Galafreian Games: The Art of Timeless Classics" when he heard a small dinging sound. Closing the book he groaned and prepared to land.


	6. Chapter Five: An End of Old Relations

**A/N:**

I do not own Harry Potter or Doctor Who, blah, blah, and blah. Now you know why I don't do this per chapter, I don't really see the point, you say it at the beginning, it stays the same for the whole thing. I really don't get why people don't put it on their main page and be done with it! Anyway, I digress, what I'm here to say is, I'm sorry it's taken me so long to update, I had a rather long summer and after finding out I got into college, I didn't really have a lot of time on my hands. This isn't a particularly long chapter, partly because I haven't had much time to write it, and partly because… well, it needed to be done, but it's not the main focus of the story.

I'm currently thinking over a one-shot parody/comedy fic but I'm drawing blanks on parts of the plot, it's set in the Potter-verse, but has a character or characters from elsewhere within… any thoughts are welcomed with open arms!!

Anywho, I'm ranting…. On with the fic I hear you cry! Enjoy

**Chapter Five: An End of Old Relations**

"Well… I guess this is it…" Harry thought as he headed towards the doors. He took a deep breath, ran a hand through his hair and flung open the doors.

The sight that lay before him angered and distressed both Harry and The Doctor to their joint core.

Diagon Alley was in uproar, over a dozen where hanging in midair grasping at their throats as if they were being strangled, others were catching fire, then being put out so their skin could heal only to be burned again, and some where literally being ripped to pieces by spherical metal orbs that had a number of different medical looking instruments protruding from them.

With a roar Harry sent a ball of raw energy at one of the orbs, which upon impact destroyed all of the orbs in the area. Harry blinked and looked at his hands.

"Well THAT'S new!" He said, turning to face his next '_target'._

In situations like this, The Doctor and Harry would _normally_ work well together, however, they were still getting used to each other…

The doctor snapped his fingers and almost at once all the people who were burning stopped and disappeared. Another snap and all the remaining choking victims also vanished so the only two people remaining in the square where The Doctor and The Master.

"Stop all this. Why do you constantly want to squash and reform the human races?" The Doctor whispered through gritted teeth.

"Because, Doctor," The Master spat, "it's always been one of the ways I'm guaranteed to see you of course!" he smiled, a proper smile, totally empty of spite. He slowly walked over to where The Doctor was standing and placed a hand on his shoulder. "Brother."

Harry looked up at the man who had murdered his mother and father.

"I'm sorry, but only half the man you knew is here, and right now, he's a bit busy." And with that Harry let out a roar and launched a rather gob smacked Voldemort into the air; Harry knew he was dead before he hit the ground a good hundred feet away. With a sad sigh, he walked back to the TARDIS and with a flick of a switch, was gone.

Witches and wizards across the country were startled when they read the front page of the Evening Prophet.

**VOLDEMORT FOUND DEAD OUTSIDE FLOREAN FORTESCUE'S ICE-CREAM PARLOR!!**

The next few weeks were full of parties throughout the wizarding world, but hardly anyone noticed the disappearance of a certain boy-who-lived.


	7. Chapter Six: Some Time Away

**Chapter Six: Some Time Away**

Harry smiled; he was lying on a beach in the Mediterranean, the evening sun warming him from head to toe. It had been five weeks since his 'Birthday Battle' in Diagon Alley. (As the Prophet had called it.) Harry was feeling much better, the double personalities had fully integrated three weeks ago but he still felt like a holiday.

He chuckled at the first few editions of the Daily Prophet mentioning his disappearance. Alien abductions and confundus charms seemed to be among the top explanations, which made Harry laugh even harder. However a few weeks previous was a totally different story.

Two weeks had past since Harry disappeared, he was eating breakfast when a post owl dropped that morning's Daily Prophet on his lap. He looked at the front page and saw his own face smiling up at him and his eyes widened as he sprayed coco pops all over the newspaper. Coughing slightly he ruffled it open and quickly read the article.

**Potter Returns A Different Man**

_After his disappearance a fortnight ago, Harry James Potter has returned to the wizarding world a changed man. Not only physically, but mentally as well. After Mr. Potter's return he was sent to St Mungo's for some private testing. The results for these tests showed us that he has two interlinked souls within his body. Within minutes of seeing these results Mr. Potter had fled the area leaving a very bemused healer trapped inside a private room._

Harry started packing all his belongings at once, though he hadn't taken much with him, he'd bought a fair amount and was chucking all he could find into the TARDIS.

However, within minutes another TARDIS appeared in the room. Harry gasped as he saw himself open the doors and smile at him.

"Well, as you can probably tell, you've not been cloned, polyjuiced or anything else." The Doctor smiled. "The truth is, 'we' wanted a holiday but 'we' didn't want people to go looking for… 'us'." The Doctor frowned and shook his head. "you know, this is going to take a lot of getting used to."

Harry laughed and stood facing himself. He noticed that instead of his usual jeans and Weasley jumper he was wearing a pinstriped suit, long brown mackintosh jacket and trainers.

"I see you've gone back to your old look then dad." They both shuddered, "ok, I guess it's weird saying dad… we really should get to the bottom of this…" Harry thought.

"Well, for now how about you call me Doctor and I call you Harry?" The Doctor smiled, leaning against _his_ TARDIS.

"Sounds fair. So, Doctor, is there anything else you came here for or do you wanna grab an early lunch?"

Both Harry's and The Doctor's stomachs rumbled in unison.

"I think that answers your own question there Harry." The Doctor chuckled. "How about a pizza and some ice cream? I know you didn't get a chance to finish breakfast and I have a craving for some right now."

Twenty minutes later Harry and The Doctor emerged from a near-by pizzeria and were making their way back to Harry's flat having decided to meet up later in the future.

Smiling at the memory, Harry sat up and walked back to his villa. His five-week break was up and today was the day he returned home, he'd made a checklist to make sure nothing was forgotten.

_1/ Tell… myself what he… I told m… him…_

_2/ Prepare my story for the Prophet_

_3/ Cheat the St Mungo's Healers so they don't detect anything… alien_

_4/ Find the gang and explain every… most of… everything…_

After double and triple checking his list Harry sighed to himself. He had nothing left to do here but he really didn't feel like going back yet. As he walked he started thinking over what he could do to pass the time. Suddenly the answer sprung to him; clicking his fingers he switched to 'Doctor Mode' and ran the rest of the way back to his villa.

He unlocked the TARDIS and ran inside, pressing buttons and flicking switches as fast as he could and within a minute the engines were roaring into life.

"See you soon old girl!" He shouted, laughing to himself. He raced back outside to watch the TARDIS disappear and grinning like a Cheshire cat he dived under his bed and pulled out his broom.

"It's been too long." He sighed. He mounted the broom and with a soft kick soared out of the open window and into the warm evening air.


End file.
